The present invention relates to batteries, and in particular, discloses batteries having indicia for measuring electrolyte levels and for determining a specific gravity correction factor for such electrolyte.
The typical lead storage battery includes a battery case which houses electrodes and electrolytes. An electrolyte is a substance in solution capable of conducting an electrical current. One common electrolyte is dilute sulfuric acid. Evaporation of water inside the battery results in a lowering of electrolyte level, and a corresponding increase in the specific gravity of the electrolyte. Addition of water to the battery to maintain electrolyte level within predetermined limits results in a raising of electrolyte level and a corresponding decrease in the specific gravity of the electrolyte. The specific gravity of the electrolyte is a good indicator of the charge of the battery. A low specific gravity may indicate an insufficiently charged battery.
"Trending" is a common practice in many factories and plants which use batteries. This procedure is used to provide an indication of battery life by comparing specific gravity readings taken over a period of time. Since specific gravity varies with the level of electrolyte within the battery, in order to properly compare like quantities over time, specific gravity readings are corrected to a predetermined reference electrolyte level. Any water additions to the battery in compensation for evaporation are made to maintain the electrolyte level at or below the reference level. A first specific gravity reading is taken with a hydrometer and the level of the electrolyte with respect to the predetermined reference level is noted while the battery is fully charged. The specific gravity reading is corrected by subtracting from the reading a predetermined specific gravity correction factor corresponding to the distance between the electrolyte level and the predetermined reference level. At predetermined intervals thereafter, additional hydrometer readings are taken. Each subsequent specific gravity reading must be corrected in the same manner as the first specific gravity reading. In this manner, proper comparisons between initial and subsequent specific gravity readings can be made.
Currently, the specific gravity correction factor is derived by manually measuring the distance between the initial electrolyte level and the level at the time of reading. This is commonly done using a conventional ruler. The specific gravity correction factor is then calculated, using the distance derived, according to manufacturer's specifications or by reference to consulting tables. Such calculations or references, however, are both time consuming and may introduce inaccuracies. For example, in a large power plant, there may be thousands of batteries for which readings must be taken. Additionally, each battery may consist of a number of cells which may require individual readings. The current procedure of taking manual readings and determining the correction factor is, therefore, burdensome and expensive.
There exists, therefore, a need for a battery which enables quick, accurate and economical reading of electrolyte level.
There also exists a need for a battery which permits quick and accurate calculation of a specific gravity correction factor.
Furthermore, there exists a need for such a battery which allows for the reading of electrolyte level and the determination of the specific gravity correction factor, but which is simple in design and inexpensive to produce.